Solder-cored wire.



V. FEESER.

SOLDER CORED WIRE.

APPLICATION FILED 1uLY7. 1914.

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vrxron FEESER, or PFORZHEIM, GERMANY, ASSIGNOR TO THE FIRM or e. nan,DOUBLEFABRIK, or PFORZI-IEIM, GERMANY.

sonnnnrconnn WIRE.

Specification of Letters Patent.

Patented July 27, 11915.

Application filed July 7, 1914. Serial No. 849,615.

To all whom it may concern:

Be it known that I, VIKTOR FEESER, a subject of the German Emperor, andresident of Pforzheim, Germany, have invented certain new and usefulImprovements in Solder- Cored Wires, of which the following is aspecification.

The hitherto known solder-cored wires contain the solder either as acylindrical pipe, which separates the inner core from the outer case, oras thin wires, which are introduced into parallel channels in theworkpiece and then rolled or drawn out with the work-piece to form finewire. In any case, apart from other drawbacks, the disadvantage existsthat it is not possible to reduce the contents of solder in the finishedwire below a certain limit, namely 4%, because the solder insertedcannot be employed be-.

low a certain thickness. Consequently, often much more solder is presentat the cut ends of the wire than is necessary for the firmness of thesoldering. For, the thinner the solder layer connecting the two wireends, the more resisting is the same especially to the torsion strainoccurring to chain links.

The present invention relates to an improved solder-cored wire, whichavoids these drawbacks and which is represented on the accompanyingdrawing, in which- Figures land 2 are cross-sections through the innercore before and after the edges of the grooves for the reception of thesolder threads are bent inward; Fig. 3 is a side view of said innercore; Fig. 4 is a sectional edge view of one end, and Fig. 5 a similarview of the other end, of the wire.

According to the present invention, the core a of the cylindrical metalpiece, out of which the wire isdrawn, is on its outside provided withseveral, for instance four, grooves, in which the solder threads I), b,which are drawn out to any fineness, are inserted (Fig. 1). The groovesmay be produced by drawing the core through a correspondingly shapeddraw-plate. Thereupon, the core a with the solder threads is drawnthrough a second draw-plate, which bends the outer edges of the groovessomewhat inward, so that now the solder threads are fixed therein andcannot escape (Fig. 2.) Thereupon, the core with the fixed solderthreads, which so far run parallel to the longitudinal axis of the core,is helically tw1sted around the latter, as shown in Fig. 3 in a sideview of the wire work-piece, which for clearness of showing is supposedto be transparent. Such twisting of the core makes the previous fixingof the solder threads absolutely necessary, as the same would otherwisebe displaced from their position in the grooves. The core with thesolderthreads thus treated is finally introduced into the case 0 (Figs.4 and 5) in a way known in the art and the wire workpiece is stretchedout-to form the finished w1re.

According to the thickness of the wire workpiece and of the finishedwire, as well as to the number of the solder threads and the requiredlength of the single wire pieces, the core with the solder threads inits grooves must be more or less twisted in order that the finishedsingle wire pieces, after being bent together for the formation of aring or link, show at their cut surfaces to be joined such a position ofthe solder ends that the latter do not touch each other but that eachsolder end at one wire end lies symmetrically between two solder ends atthe other wire end (see Figs. 4 and 5).

Consequently, the actual expansion of the solder, which eventually actsto drive the joint asunder, is considerably decreased and the escapingsolder comes in touch with the 'main metal at double as many points assolder threads are present. Thereby, a uniform distribution of thesolder and a thinner solder joint is obtained. I

By the outer case remaining untwisted, as above described, alldifficulties for the further treatment are avoided and every security isafforded that the wire, after being finally drawn and cut into pieces,shows the required twist of the solder threads.

I claim:

A solder-cored wire, comprising a plurality of solder threads, a corehaving longitudinal groove s on its outside for the recept-ion of saidsolder threads and bent inward edges on said grooves to fix the solderthreads therein, said core with solder 5 threads beinghelically twistedaround the longitudinal axis of the core,- and a. straight

